src/lxc/af_unix.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <daniel.lezcano at free.fr>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23 #include "config.h"
  24
  25 #include <errno.h>
  26 #include <fcntl.h>
  27 #include <stddef.h>
  28 #include <stdio.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <unistd.h>
  32 #include <sys/socket.h>
  33 #include <sys/syscall.h>
  34 #include <sys/un.h>
  35
  36 #include "log.h"
  37 #include "utils.h"
  38
  39 #ifndef HAVE_STRLCPY
  40 #include "include/strlcpy.h"
  41 #endif
  42
  43 lxc_log_define(lxc_af_unix, lxc);
  44
  45 int lxc_abstract_unix_open(const char *path, int type, int flags)
  46 {
  47         int fd, ret;
  48         size_t len;
  49         struct sockaddr_un addr;
  50
  51         fd = socket(PF_UNIX, type, 0);
  52         if (fd < 0)
  53                 return -1;
  54
  55         /* Clear address structure */
  56         memset(&addr, 0, sizeof(addr));
  57
  58         if (!path)
  59                 return fd;
  60
  61         addr.sun_family = AF_UNIX;
  62
  63         len = strlen(&path[1]);
  64         /* do not enforce \0-termination */
  65         if (len >= sizeof(addr.sun_path)) {
  66                 close(fd);
  67                 errno = ENAMETOOLONG;
  68                 return -1;
  69         }
  70
  71         /* do not enforce \0-termination */
  72         memcpy(&addr.sun_path[1], &path[1], len);
  73
  74         ret = bind(fd, (struct sockaddr *)&addr,
  75                    offsetof(struct sockaddr_un, sun_path) + len + 1);
  76         if (ret < 0) {
  77                 int tmp = errno;
  78                 close(fd);
  79                 errno = tmp;
  80                 return -1;
  81         }
  82
  83         if (type == SOCK_STREAM) {
  84                 ret = listen(fd, 100);
  85                 if (ret < 0) {
  86                         int tmp = errno;
  87                         close(fd);
  88                         errno = tmp;
  89                         return -1;
  90                 }
  91
  92         }
  93
  94         return fd;
  95 }
  96
  97 int lxc_abstract_unix_close(int fd)
  98 {
  99         close(fd);
 100         return 0;
 101 }
 102
 103 int lxc_abstract_unix_connect(const char *path)
 104 {
 105         int fd, ret;
 106         size_t len;
 107         struct sockaddr_un addr;
 108
 109         fd = socket(PF_UNIX, SOCK_STREAM, 0);
 110         if (fd < 0)
 111                 return -1;
 112
 113         memset(&addr, 0, sizeof(addr));
 114
 115         addr.sun_family = AF_UNIX;
 116
 117         len = strlen(&path[1]);
 118         /* do not enforce \0-termination */
 119         if (len >= sizeof(addr.sun_path)) {
 120                 close(fd);
 121                 errno = ENAMETOOLONG;
 122                 return -1;
 123         }
 124
 125         /* do not enforce \0-termination */
 126         memcpy(&addr.sun_path[1], &path[1], len);
 127
 128         ret = connect(fd, (struct sockaddr *)&addr,
 129                       offsetof(struct sockaddr_un, sun_path) + len + 1);
 130         if (ret < 0) {
 131                 close(fd);
 132                 return -1;
 133         }
 134
 135         return fd;
 136 }
 137
 138 int lxc_abstract_unix_send_fds(int fd, int *sendfds, int num_sendfds,
 139                                void *data, size_t size)
 140 {
 141         int ret;
 142         struct msghdr msg;
 143         struct iovec iov;
 144         struct cmsghdr *cmsg = NULL;
 145         char buf[1] = {0};
 146         char *cmsgbuf;
 147         size_t cmsgbufsize = CMSG_SPACE(num_sendfds * sizeof(int));
 148
 149         memset(&msg, 0, sizeof(msg));
 150         memset(&iov, 0, sizeof(iov));
 151
 152         cmsgbuf = malloc(cmsgbufsize);
 153         if (!cmsgbuf)
 154                 return -1;
 155
 156         msg.msg_control = cmsgbuf;
 157         msg.msg_controllen = cmsgbufsize;
 158
 159         cmsg = CMSG_FIRSTHDR(&msg);
 160         cmsg->cmsg_level = SOL_SOCKET;
 161         cmsg->cmsg_type = SCM_RIGHTS;
 162         cmsg->cmsg_len = CMSG_LEN(num_sendfds * sizeof(int));
 163
 164         msg.msg_controllen = cmsg->cmsg_len;
 165
 166         memcpy(CMSG_DATA(cmsg), sendfds, num_sendfds * sizeof(int));
 167
 168         iov.iov_base = data ? data : buf;
 169         iov.iov_len = data ? size : sizeof(buf);
 170         msg.msg_iov = &iov;
 171         msg.msg_iovlen = 1;
 172
 173         ret = sendmsg(fd, &msg, MSG_NOSIGNAL);
 174         free(cmsgbuf);
 175         return ret;
 176 }
 177
 178 int lxc_abstract_unix_recv_fds(int fd, int *recvfds, int num_recvfds,
 179                                void *data, size_t size)
 180 {
 181         int ret;
 182         struct msghdr msg;
 183         struct iovec iov;
 184         struct cmsghdr *cmsg = NULL;
 185         char buf[1] = {0};
 186         char *cmsgbuf;
 187         size_t cmsgbufsize = CMSG_SPACE(num_recvfds * sizeof(int));
 188
 189         memset(&msg, 0, sizeof(msg));
 190         memset(&iov, 0, sizeof(iov));
 191
 192         cmsgbuf = malloc(cmsgbufsize);
 193         if (!cmsgbuf)
 194                 return -1;
 195
 196         msg.msg_control = cmsgbuf;
 197         msg.msg_controllen = cmsgbufsize;
 198
 199         iov.iov_base = data ? data : buf;
 200         iov.iov_len = data ? size : sizeof(buf);
 201         msg.msg_iov = &iov;
 202         msg.msg_iovlen = 1;
 203
 204         ret = recvmsg(fd, &msg, 0);
 205         if (ret <= 0)
 206                 goto out;
 207
 208         cmsg = CMSG_FIRSTHDR(&msg);
 209
 210         memset(recvfds, -1, num_recvfds * sizeof(int));
 211         if (cmsg && cmsg->cmsg_len == CMSG_LEN(num_recvfds * sizeof(int)) &&
 212             cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
 213                 memcpy(recvfds, CMSG_DATA(cmsg), num_recvfds * sizeof(int));
 214         }
 215
 216 out:
 217         free(cmsgbuf);
 218         return ret;
 219 }
 220
 221 int lxc_abstract_unix_send_credential(int fd, void *data, size_t size)
 222 {
 223         struct msghdr msg = {0};
 224         struct iovec iov;
 225         struct cmsghdr *cmsg;
 226         struct ucred cred = {
 227             .pid = lxc_raw_getpid(), .uid = getuid(), .gid = getgid(),
 228         };
 229         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 230         char buf[1] = {0};
 231
 232         msg.msg_control = cmsgbuf;
 233         msg.msg_controllen = sizeof(cmsgbuf);
 234
 235         cmsg = CMSG_FIRSTHDR(&msg);
 236         cmsg->cmsg_len = CMSG_LEN(sizeof(struct ucred));
 237         cmsg->cmsg_level = SOL_SOCKET;
 238         cmsg->cmsg_type = SCM_CREDENTIALS;
 239         memcpy(CMSG_DATA(cmsg), &cred, sizeof(cred));
 240
 241         msg.msg_name = NULL;
 242         msg.msg_namelen = 0;
 243
 244         iov.iov_base = data ? data : buf;
 245         iov.iov_len = data ? size : sizeof(buf);
 246         msg.msg_iov = &iov;
 247         msg.msg_iovlen = 1;
 248
 249         return sendmsg(fd, &msg, MSG_NOSIGNAL);
 250 }
 251
 252 int lxc_abstract_unix_rcv_credential(int fd, void *data, size_t size)
 253 {
 254         struct msghdr msg = {0};
 255         struct iovec iov;
 256         struct cmsghdr *cmsg;
 257         struct ucred cred;
 258         int ret;
 259         char cmsgbuf[CMSG_SPACE(sizeof(cred))] = {0};
 260         char buf[1] = {0};
 261
 262         msg.msg_name = NULL;
 263         msg.msg_namelen = 0;
 264         msg.msg_control = cmsgbuf;
 265         msg.msg_controllen = sizeof(cmsgbuf);
 266
 267         iov.iov_base = data ? data : buf;
 268         iov.iov_len = data ? size : sizeof(buf);
 269         msg.msg_iov = &iov;
 270         msg.msg_iovlen = 1;
 271
 272         ret = recvmsg(fd, &msg, 0);
 273         if (ret <= 0)
 274                 goto out;
 275
 276         cmsg = CMSG_FIRSTHDR(&msg);
 277
 278         if (cmsg && cmsg->cmsg_len == CMSG_LEN(sizeof(struct ucred)) &&
 279             cmsg->cmsg_level == SOL_SOCKET &&
 280             cmsg->cmsg_type == SCM_CREDENTIALS) {
 281                 memcpy(&cred, CMSG_DATA(cmsg), sizeof(cred));
 282                 if (cred.uid &&
 283                     (cred.uid != getuid() || cred.gid != getgid())) {
 284                         INFO("message denied for '%d/%d'", cred.uid, cred.gid);
 285                         return -EACCES;
 286                 }
 287         }
 288 out:
 289         return ret;
 290 }